This invention relates to an oil cooler comprising a housing with connections for the supply and removal of a coolant, and comprising several hollow disks or plates through which the oil flows that is to be cooled. The disks are aligned and are connected with one another by means of their interiors and are fitted onto a hollow screw provided in the housing. The hollow screw is used for the fastening of the housing on the engine block and for the connection to a recirculating bore for the oil which flows off through the hollow screw through the interiors of the hollow disks and by way of a chamber, which is situated on the side of the housing facing away from the engine block and bounded by a circular wall.
Oil coolers of this type are known (U.S. Pat. Nos. 4,360,055 and 4,561,494). These oil coolers are used in connection with an oil filter which is placed on the side of the oil cooler facing away from the engine block and is held by the hollow screw. If such oil coolers are to be used without a filter, it is necessary, as a rule, to change the housing and the bundle of hollow plates or disks in such a manner that oil will no longer flow out on the side facing away from the engine block. It is therefore necessary to provide different oil coolers, depending on whether they are to be used together with an oil filter or without one. This requires high expenditures.
It is true that it is known from U.S. Pat. No. 4,669,532 to close off an oil cooler of the initially mentioned type having an open housing on the side facing away from the engine block by means of a separate housing cover which, by means of a sealing device, is placed on the outside on a ring area of the housing and is held on the housing by means of a hollow screw which projects into a dome of the cover by means of a threaded pipe and, in the space between the dome and a hexagon, has bores for the connection of the chamber formed inside the cover with the interior of the hollow screw. However, constructions of this type, because of the additional cover, take up a relatively large amount of space which is sometimes not available in motor vehicles. In addition, the mounting of the closing cover results in relatively high expenditures.
It is therefore an object of the invention to develop an oil cooler of the initially mentioned type in such a manner that it is suitable for use with a filter as well as for use without a filter and can be made available for the respective desired use without any expenditures.
In order to achieve this object, it is provided in the case of an oil cooler of the initially mentioned type that the hollow screw, on the side of the driving surfaces for a screwing tool which is directed toward the housing, is provided with a closing disk which is mounted on it in a collar-type manner and which is provided with a sealing surface resting against the annular wall, and because of the fact that, on the side of the end disk facing the housing, an opening is provided which leads into the interior of the hollow screw. Because of this development, the hollow screw, which is to be provided for use with the filter and is open on both ends, must only be replaced by the hollow screw with the end disk in which case the driving surfaces for a screwing tool, which are provided on the hollow screw which is closed on one side, may be used in a simple manner also for the sealing-off of the end disk. In this case, it is possible to place the sealing surface in each case on the circumference of the end disk and let it interact with the surface of the annular wall directed toward the interior, or to arrange the sealing surface on the side of the end wall which points in the direction of the housing and to let it interact with the face of the annular wall pointing toward the exterior. Particularly in the former case, where the end wall of the hollow screw is situated almost completely sunk inside the space of the annular wall, an extremely space-saving construction is achieved. The handling of the hollow screw is simple in either case.
It is particularly advantageous according to certain preferred embodiments to provide, on the side of the housing facing away from the chamber, in addition to the feeding opening of the first hollow disk connected to the inflow coming from the engine block, an additional opening in the housing and in the side of the first hollow disk bordering on the housing which can be kept closed by means of a pressure control valve which is disposed on the interior side of the hollow disk and opens toward the inside. By means of this development, it also becomes possible in the case of the compact space-saving construction according to the initially mentioned invention to let engine oil very rapidly flow through the oil cooler when the oil is still cold and correspondingly viscous. The reason is that the valve arrangement situated on the engine side, in such a case, opens the direct flow-through path through the hollow disks so that an excessive pressure loss can be avoided.
It is true that it is basically known in the case of disk oil coolers to provide such valves which open at higher pressures. U.S. Pat. No. 4,669,532, for example, shows such a helically constructed valve. U.S. Pat. No. 3,743,011 is also provided with such a valve within the range of the hollow screw, and U.S. Pat. No. 4,360,055 shows a bow-shaped valve in the space between the filter and the oil cooler housing. In the case of the present further development of the invention, however, the valve is arranged on the other side of the oil cooler housing, specifically on the side facing the engine block, specifically while opening toward the interior. This development makes it possible to provide a disk oil cooler with such a valve without any additional space requirement for the arrangement of the valve on the side of the housing facing away from the engine block. It is also advantageous for the hollow screw and the end disk to be constructed in two parts because, as a result, the manufacturing costs may be kept low.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.